The subject matter disclosed herein relates to an apparatus for driving shaft rotation and, more particularly, to a synchronous machine with a load commutated inverter for high speed start and reduced shutdown duration of a machine.
Driving elements, such as synchronous motor drives with or without load commutated inverters (LCIs), can be used to start any machine or gas turbine engine from a stand still condition or a base speed of about 3-6 rpm. For gas turbine engines in particular, such driving elements are required because gas turbine engines themselves are not self-starting machines. The driving elements are used to bring the gas turbine engines to nearly full speed no load conditions. Typically, this is achieved by coupling a driving element to the rotor of a gas turbine engine whereby the driving element acts as a motor that accelerates the rotor to the speeds at which the gas turbine engine achieves self-sustained operation.
Normally, driving elements are not equipped with a capability to start the machine or gas turbine engine at speeds higher than base or turning gear speed. Because of this constraint, in the exemplary case of a gas turbine engine trip at a high speed, it is necessary to wait until the gas turbine engine roles down to 0 RPMs or the base or turning gear speed before a restart can be initiated. This can sometimes take a relatively long time and lead to economic losses.